LOSSES DUE TO CROWN-GALL. 191 



cent formalin the senior writer saw bacteria in the browned outer 

 crevices much hke those described by Cuboni (1.5x0.3 to 0.5 //), but 

 less numerous and not likely to be the parasite. 



RED CLOVER. 



Galls have been found on roots of red clover (Trifolium pratense) 

 in Kentucky and Alabama. It is not yet known how destructive 

 this organism is when it gains entrance to a clover field. 



ALFALFA. 



Roots with tubercles other than the nitrogen-fixing nodules have 

 been found on alfalfa plants {Medicago sativa) in Kentucky, Mary- 

 land, Pennsylvania, Alabama, and New York (?). The galls are 

 found on plants in fields where the stand is very poor and also an 

 occasional gall is found on plants in very good fields. The plants 

 affected do not grow to full size, but it is not yet known whether they 

 are killed directly by the work of the gall organism or not, although 

 large portions of fields die and the roots are found more or less 

 affected with galls. 



COTTON. 



The crown-gall of the cotton plant (Gossypium sp.) occurs rarely 

 (so far as our information goes) and is not known to cause any 

 trouble whatever to the growers of cotton. It has been found in 

 Texas and also on the crown of cotton plants growing in the green- 

 house in Washington. 



HOPS. 



The reports of hop growers on the Pacific coast indicate that this 

 disease may do considerable damage, particularl}'' as the galls often 

 reach a diameter of one's double fist. Some believe that an attack 

 of tw^o years' duration is sufficient to kill a plant. According to Dr. 

 W. W. Stockberger, of this Bureau, the disease occurs on hops not 

 only in Washmgton State and Oregon, but also in the Sacramento 

 valley in California: "There I have seen acres of hops in which 

 scarcely a hill could be found which did not show these tumors, some 

 of them being larger than my fist." 



SUGAR BEETS. 



A crown-gall also occurs naturally on the sugar beet both in this 

 country and in Europe. While rather rare in the United States, it 

 appears to be widely distributed, and more common some seasons 

 than others. We have received specimens from localities as widely 

 separated as Virginia, Michigan, South Dakota, Utah, Cahfornia, 



213 



